Abstract

Background
Cancer and Diabetes Mellitus (DM) are leading causes of death worldwide and the prevalence
of both is escalating. People with co-morbid cancer and DM have increased morbidity and
premature mortality compared with cancer patients with no DM. The reasons for this are likely
to be multifaceted but will include the impact of hypo/hyperglycaemia and diabetes therapies
on cancer treatment and disease progression. A useful step toward addressing this disparity
in treatment outcomes is to establish the impact of cancer treatment on diabetes control.
Aim
The aim of this review is to identify and analyse current evidence reporting glycaemic control
(HbA1c) during and after cancer treatment. Methods
Systematic searches of published quantitative research relating to comorbid cancer and
type 2 diabetes mellitus were conducted using databases, including Medline, Embase, PsychINFO,
CINAHL and Web of Science (February 2017). Full text publications were eligible
for inclusion if they: were quantitative, published in English language, investigated the
effects of cancer treatment on glycaemic control, reported HbA1c (%/mmols/mol) and
included adult populations with diabetes. Means, standard deviations and sample sizes
were extracted from each paper; missing standard deviations were imputed. The completed
datasets were analysed using a random effects model. A mixed-effects analysis was undertaken
to calculate mean HbA1c (%/mmols/mol) change over three time periods compared
to baseline.
Results
The available literature exploring glycaemic control post-diagnosis was mixed. There was
increased risk of poor glycaemic control during this time if studies of surgical treatment for
gastric cancer are excluded, with significant differences between baseline and 12 months
(p < 0.001) and baseline and 24 months (p = 0.002).
Conclusion
We found some evidence to support the contention that glycaemic control during and/or
after non-surgical cancer treatment is worsened, and the reasons are not well defined in
individual studies. Future studies should consider the reasons why this is the case.